Abda F, Azbaid A, Ensminger D, Fischer S, François P, Schmitt P, Pallarès A
Institut de Mécanique des Fluides et des Solides de Strasbourg, 2-4 rue Boussingault, 67000 Strasbourg, France.
Water Sci Technol. 2009;60(1):117-25. doi: 10.2166/wst.2009.281.
In the frame of a technological research and innovation network in water and environment technologies (RITEAU, Réseau de Recherche et d'Innovation Technologique Eau et Environnement), our research group, in collaboration with industrial partners and other research institutions, has been in charge of the development of a suitable flowmeter: an ultrasonic device measuring simultaneously the water flow and the concentration of size classes of suspended particles. Working on the pulsed ultrasound principle, our multi-frequency device (1 to 14 MHz) allows flow velocity and water height measurement and estimation of suspended solids concentration. Velocity measurements rely on the coherent Doppler principle. A self developed frequency estimator, so called Spectral Identification method, was used and compared to the classical Pulse-Pair method. Several measurements campaigns on one wastewater collector of the French city of Strasbourg gave very satisfactory results and showed smaller standard deviation values for the Doppler frequency extracted by the Spectral Identification method. A specific algorithm was also developed for the water height measurements. It relies on the water surface acoustic impedance rupture and its peak localisation and behaviour in the collected backscattering data. This algorithm was positively tested on long time measurements on the same wastewater collector. A large part of the article is devoted to the measurements of the suspended solids concentrations. Our data analysis consists in the adaptation of the well described acoustic behaviour of sand to the behaviour of wastewater particles. Both acoustic attenuation and acoustic backscattering data over multiple frequencies are analyzed for the extrapolation of size classes and respective concentrations. Under dry weather conditions, the massic backscattering coefficient and the overall size distribution showed similar evolution whatever the measurement site was and were suggesting a global wastewater particles behaviour. By comparison to sampling data, our data analysis lead to the characterization of two particle groups: the ones occurring during rain events and the ones typical of wastewater under dry weather conditions. Even with already encouraging results on the several weeks of data recorded on several wastewater collectors, the validation of our data inversion method is still under progress.
在水与环境技术领域的技术研究与创新网络（RITEAU，水与环境技术研究与创新网络）框架内，我们的研究小组与工业合作伙伴及其他研究机构合作，负责开发一种合适的流量计：一种能同时测量水流和悬浮颗粒粒径分级浓度的超声设备。基于脉冲超声原理，我们的多频设备（1至14兆赫兹）可进行流速、水位测量以及悬浮固体浓度估算。流速测量基于相干多普勒原理。使用了一种自行开发的频率估计器，即所谓的频谱识别方法，并与经典的脉冲对方法进行了比较。在法国斯特拉斯堡市的一个污水收集器上进行的多次测量活动取得了非常令人满意的结果，结果表明频谱识别方法提取的多普勒频率的标准差更小。还开发了一种用于水位测量的特定算法。它基于水面声阻抗破裂及其在采集的反向散射数据中的峰值定位和行为。该算法在对同一污水收集器的长时间测量中得到了肯定的测试。文章的很大一部分致力于悬浮固体浓度的测量。我们的数据分析包括将已充分描述的沙子声学行为应用于污水颗粒的行为。分析多个频率上的声衰减和声学反向散射数据，以推断粒径分级和各自的浓度。在干燥天气条件下，无论测量地点如何，质量反向散射系数和总体粒径分布都呈现出相似的变化趋势，这表明了污水颗粒的整体行为。通过与采样数据比较，我们的数据分析确定了两类颗粒：降雨事件期间出现的颗粒和干燥天气条件下典型的污水颗粒。即使在几个污水收集器上记录的数周数据已经取得了令人鼓舞的结果，但我们的数据反演方法的验证仍在进行中。
